G'Day Guys just got this terrific machine but after the weekend found a few probs. Starts easily and runs well rc valves missing outer cables, i just fixed them with springs at the optimum level, seems to work ok (track bike only).A strange thing occurs at idle, rear pot runs heaps cooler with a much reduced exhaust pressure, can put hand over exhaust on that pot and engine still runs but not on the other one! Seems to be fine from about 5000 rpm on. Main questions will leaving the RC valves in one position cause engine damage and why the pressure difference? many thanks , this is a terrific site, heaps of great info very , very usefull.

P.S plugs and pistons correct colour and the same(dak brown and black)

It's "normal" (well, "NSR normal"!) for the two cylinders to run differently at idle, but if the idle is VERY different cylinder-to-cylinder, then I would look at the compression.

If the compression is low it can cause a misfire, then as the rev's rise, things generally tend to get a bit better!

Running the motor with the RC Valves fixed in one position won't hurt the motor; just possibly make it harder to start/run at low rpm.

Andy.
NSR-WORLD.COM

Good for you jc,
I also got a MC21 about a month ago. Still trying to learn more about the bike. Too bad I don't have a garage where I can take the bike apart and learn all the structure. I have to rely on local mechanics to keep my bike running. Happy reving.